This is great! I have a question, though:
I have a guppy that is in a two gallon bowl without a filter or a heater (none of my tanks have heaters, but they all stay at about 78 degrees). I did a 100 percent water change yesterday, so the water is all pretty new. I just now learned about cycling and I'm pretty sure my three tanks already are cycled without me even trying to do it (I've heard that this is pretty common.) The ammonia in my three filtered tanks stay at about 0.00ppm. Could I just add an extra piece of décor from one of my cycled tanks to cycle my new tank even though it doesn't have a filter? Thanks! And I am pretty sure that the female guppy in my bowl is pregnant, so I don't have any gravel. I've heard that this is best for when she gives birth, is this true? So even though I don't have gravel will I be able to cycle the tank? Thank you so much for all of this information!

You need a filter to cycle a tank; to keep the water circulating over the bacteria. It would help to have more than a piece of decor to help kickstart the new cycle. Try putting some established/cycled filter material or substrate in your new filter.

Bare-bottom tanks cycle just as easilly as ones with substrate. The key is to have enough filter foam or other surface area to house the nitrifying bacteria. It really doesn't take all that much.

Leaf litter (Oak or Indian Almond, etc) makes an excellent substrate for fry.. Lots of infusoria for first-food.

Thanks for the info! I've read so many different guides on cycling that I have no idea if I have done anything right. One site said that a tank smaller than 5 gallons can't be cycled. I have a 1.5 gallon with a filter, live plant and one betta. I'm not sure what the plant is but I think it might be an Amazon? My fish was rescued after being left in an empty house for several days. He was in a tiny bowl that probably held about 5 cups of water, no filter and only plastic plants. The 1.5 gallon tank came with a filter, pump, cover and light which was all I could afford at the time. I put in some of the gel marbles out of his old bowl but everything else was new. I used spring water to fill his tank and he has done remarkably well. I read that water conditioner isn't necessary when using spring water. He wouldn't eat for the first couple of days, except for a flake or two of tropical food, but now eats two pellets twice a day. I have been doing 25 to 30% water changes twice a week, also with spring water. He builds big bubble nests and knows my voice.
I don't have a water test kit and was wondering if there is a good, relatively inexpensive kit you could recommend. I have a TDS meter, but nothing to tell the amounts of ammonia, nitrites or nitrates. Also, his plant is in crushed granite with marbles covering the rest of the tank floor. It's got a few brown leaves and some of the leaf tips are turning brown. Should I remove the dead leaves? What can I do to keep this plant from dying? Also, on another site I read that some of the old filter should be added when changing to a new filter. Is that something you would recommend?

A 1.5g tank can be cycled, but it requires close monitoring with a liquid test kit, especially if you're going to try cycling with the fish in the tank.

Most keepers who run such small tanks either perform 2x weekly water changes or become familiar with plants, enough to maintain a "planted tank." In combination with a filter, this is the safest method for your fish and, although more work, is a satisfying part of the hobby for many.

Good plants for a small tank are fast-rowing rooted plants and floating plants. Check the "planted tank" section for more detailed info.

The plant you have is probably an Anubias, right?....a very pretty low-light plant, but not much help keeping ammonia under control.

alright, so i was just going to make a new post but you know what? no I will post my question here. I feel like its been asked a million times before, I've seen the answer somewhere and yet clearly now I am losing my mind and can't find it. SO.
During the fishless cycle, I understand that if the nitrATES get too high, it can stall the cycle and a water change is necessary. What is that amount? I ask because I am in the middle of a fishless cycle using fish food. I am 2 weeks in. My readings using the API Master test kit are as follows:
Ammo: 0-0.25ppm
nitrITES: 5+ ppm
nitrATES: 40 ppm
Should I do a water change to get the nitrates down or should i leave them?
Thanks in advance!